U.S. patent application number 14/002745 was filed with the patent office on 2014-11-20 for automatic lens mapping system.
This patent application is currently assigned to Visionix LTD. The applicant listed for this patent is Nir Amiel, Ran Yam. Invention is credited to Nir Amiel, Ran Yam.
Application Number | 20140340672 14/002745 |
Document ID | / |
Family ID | 49680740 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140340672 |
Kind Code |
A1 |
Yam; Ran ; et al. |
November 20, 2014 |
AUTOMATIC LENS MAPPING SYSTEM
Abstract
A system for holding and aligning spectacles such that mapping
measurements of the optical properties of a lens can be performed
with the lens held such that its optical axis is parallel to the
incident measurement beam. This may be implemented using three
points which define a plane with which a surface of the lens can be
aligned. The frame gripper is constructed such that the lens to be
measured is free to rotate in space around any axis until clamped
by the three alignment pin support arrangement, with the exception
of rotation around the optical axis of the lens. This freedom of
rotation allows the lens to be positioned on the alignment pin
support automatically without the need for operator intervention.
The spectacle frame is clamped using a spring loaded caliper
device, configured to sequentially align the mechanical center of
each lens with the measuring beam.
Inventors: |
Yam; Ran; (Jerusalem,
IL) ; Amiel; Nir; (Zur Hadassa, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yam; Ran
Amiel; Nir |
Jerusalem
Zur Hadassa |
|
IL
IL |
|
|
Assignee: |
Visionix LTD
Jerusalem
IL
|
Family ID: |
49680740 |
Appl. No.: |
14/002745 |
Filed: |
March 4, 2012 |
PCT Filed: |
March 4, 2012 |
PCT NO: |
PCT/IL12/00107 |
371 Date: |
August 4, 2014 |
Current U.S.
Class: |
356/124 |
Current CPC
Class: |
G01M 11/0214 20130101;
G02C 13/003 20130101; G01M 11/0235 20130101 |
Class at
Publication: |
356/124 |
International
Class: |
G02C 13/00 20060101
G02C013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2011 |
US |
91448692 |
Claims
1. A system for measurement of the optical properties of spectacle
lenses, comprising: a source of light for transmitting a light beam
through a lens to be measured; an optical analyzing unit for
analyzing the light beam after transmission through said lens; a
lens aligner disposed in the path of said light beam before said
optical analyzing unit, said lens aligner defining a plane
perpendicular to the path of said light beam; a mechanism for
pressing said lens into position on said lens aligner; a frame
gripper for gripping the lenses of said spectacles; and a
mechanical structure adapted to enable said frame gripper, before
clamping of said lens on said lens aligner, to rotate said
spectacles freely about both axes orthogonal to that parallel to
the path of said light beam.
2. A system according to claim 1, wherein said lens aligner is a
set of three alignment pins.
3. A system according to claim 1, wherein said lens aligner is an
alignment ring.
4. A system according to claim 1, wherein said frame gripper is
adapted to center said lens at the center of said lens aligner when
said lens is positioned laterally over said lens aligner.
5. A system according to claim 4 wherein said frame gripper
comprises a crossed pair of arms connected in their central region
by a pivot joint, each arm comprising a lens gripper at locations
on said arm at opposite sides of said pivot, and wherein said frame
gripper is disposed in said system such that said pivot joint lies
at the center of said lens aligner when said holder is in its
central position.
6. A system according to claim 5 wherein said arms comprise
gripping elements at or near their extremities, said gripping
elements being adapted to grip the edges of said lenses.
7. A system according to claim 5 wherein said arms are spring
loaded in such a manner as to bias them to grip the edges of said
lenses.
8. A system according to claim 5 wherein said frame gripper
comprises a ratchet locking mechanism adapted to hold said
spring-loaded arms open until said ratchet is released.
9. A system according to claim 5 wherein said frame gripper
comprises a support wire positioned beneath said arms, such that
said spectacles are supported thereon while not yet gripped by said
frame gripper.
10. A system according to claim 5 wherein said pivot lies on a line
joining the centers of both lenses of said spectacles when gripped
in said frame gripper.
11. A system according to claim 1, wherein said lens aligner
defining said plane perpendicular to the path of said light beam
enables measurement of said lens to be performed with an accuracy
independent of either of the optical sag or tilt of said lens.
12. A system according to claim 2, wherein said mechanism for
pressing said lens into position on said lens aligner comprises a
set of spring loaded pins, each pin being disposed essentially
opposite to one of said alignment pins.
13. A system according to claim 1, wherein said mechanical
structure comprises a journal and bush bearing enabling said frame
gripper to perform roll motion, and a double pivot assembly
enabling said frame gripper to perform pitch motion and vertical
motion.
14. A system according to claim 13, wherein said journal and bush
bearing comprises a cylindrical journal attached to said frame
gripper, adapted to rotate within a bush bearing formed in a base
assembly, said base assembly being attached to a mounting assembly
connected to horizontal and vertical movement slides on said
system.
15. A system according to claim 13, wherein said double pivot
assembly comprises a base assembly to which said frame gripper is
rotatably attached, said base assembly being attached at each of
its sides by a first pivot joint to a pivot arm, said pivot arm on
each side of said double pivot assembly being attached at an end
remote from said first pivot joint by means of a second pivot joint
to a mounting assembly connected to horizontal and vertical
movement slides on said system.
16. A system according to claim 13, further comprising an actuator
element attached to a controlled vertical motion mechanism, wherein
said mechanical structure is attached flexibly to said actuator
element, such that when said actuator element is lowered, said
structural element is also lowered.
17. A system according to claim 16, wherein said controlled
vertical motion mechanism also lowers said mechanism for pressing
said lens into position on said lens aligner.
18. A system according to claim 1, further comprising a controlled
horizontal motion mechanism, such that said frame gripper can be
moved laterally between lenses.
19. A system according to claim 1, further comprising control
circuitry adapted to control said vertical and horizontal motion
mechanisms in conjunction with said optical analyzing unit for
analyzing the light beam after transmission through said lens, such
that said measurement of the optical properties of spectacle lenses
is performed on both lenses sequentially and automatically.
20. A system according to claim 1, wherein the position of the
pivot of the arms of said frame gripper is configured such that the
mechanical center of each lens is aligned longitudinally with the
axis of said light beam when said lens is positioned over said lens
aligner.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of lens mapping
systems using self-centering spectacle frame holders, especially
for use in automatic measuring systems.
BACKGROUND OF THE INVENTION
[0002] A number of instruments exist for mapping optical elements,
and especially for ophthalmic use. Such instruments generally use a
Hartman Shack matrix for analyzing the refractions of a beam of
light transmitted through the spectacle lens. In U.S. Pat. No.
5,825,476, there is described such a system, and other such systems
are cited in that patent. One of the major disadvantages of many of
such prior art instruments is that the user places the spectacle
frames directly on the measurement table, such that the reference
plane used to align the lenses is then effectively that of the
frame itself, and not of the lenses being mapped. Consequently, if
the lens form has a large element of sag, or if the lens has a
large tilt, then the mapping results obtained may be inaccurate.
Furthermore, in many such prior art instruments, the frames have to
be aligned manually or by means of motors in order to align the
mechanical center of the lenses being measured with the measurement
beam.
[0003] There therefore exists a need for a spectacle measurement
system, which can map both lenses automatically and which overcomes
at least some of the disadvantages of prior art systems and
methods.
[0004] The disclosures of each of the publications mentioned in
this section and in other sections of the specification, are hereby
incorporated by reference, each in its entirety.
SUMMARY OF THE INVENTION
[0005] The present disclosure describes new exemplary systems for
holding and aligning spectacles such that mapping measurements of
the optical properties of the lenses can be performed by the user
accurately and speedily. The systems utilize a novel lens aligning
system, which ensures that the lens being measured adopts a
position with the incident measurement beam parallel to the optical
axis of the lens. The lens aligning device may most conveniently be
implemented using three points which define a plane with which the
lens surface can be aligned. This can be achieved by a set of
aligning pins against which one surface of the lens is forced,
preferably by a similar set of spring-loaded pressure pins which
descend on to the lens to force it against the aligning pins. This
arrangement ensures that the lens is always in a predetermined
position with the measurement beam incident on the lens normally,
independent of the amount of sag or tilt of the lens being
measured. A three pin system is the most advantageous arrangement,
since all three pins will always be in contact with the lens
surface regardless of the surface profile. However, it is to be
understood that the invention is not mean to be limited to three
pin implementations, but that any other lens aligner device is
equally acceptable, such as a ring, so long as the element defines
a plane perpendicular to the measurement beam, and that it does not
obscure more than a minimal part of the beam path. For convenience,
the systems of the present disclosure will be described hereinbelow
in terms of the three-pin arrangement, though it is to be
understood that this is just one possible implementation.
[0006] The system utilizes a novel mechanical holding system which
ensures that the lenses are held normal to the measurement light
beam, with each lens sequentially positioned over the center of the
alignment pins, so that the light passes through the lens in the
region of its mechanical center, or through any other predetermined
location desired on the lens. Once the spectacle frames have been
inserted into the system, the alignment procedure is performed
semi-automatically. The clamping system is such that the spectacle
frame is free to rotate around all axes and move in the vertical
direction while being clamped, such that each lens adopts the
optimum position on the alignment pins in the measurement system
regardless of the profile of the lens surface. The exception to
this is that freedom of rotation is not permitted around the axis
perpendicular to the lens, since such freedom of rotation would
produce an incorrect reading of the measured cylinder axis of the
lens.
[0007] A novel aspect of the system from the point of view of the
optics is thus that it enables mapping of the lens to be performed
without errors induced by lack of knowledge of the tilt or sag of
the lens, since the use of the three alignment pin support enables
the instrument to bring the lens to a predefined plane
perpendicular to the incident measurement beam, essentially
regardless of the form of the lens.
[0008] A novel aspect of the system from the point of view of the
mechanics is thus that the frame incorporating the lens to be
measured is held in such a manner that it is free to rotate in
space around any axis until clamped by the three alignment pin
support arrangement, with the exception of rotation around the
optical axis of the lens, as previously explained. This freedom of
rotation is what allows the lens to be positioned on the alignment
pin support automatically without the need for operator
intervention. In general, the freedom of rotation of the frame is
described, and is also thuswise claimed, in terms of the Tait-Bryan
angles, (or the aeronautical nomenclature for the axes of rotation
derived therefrom), in which the yaw axis is the vertical axis
parallel to the direction of the light measuring beam and hence
perpendicular to the lens being measured, the pitch axis is the
lateral axis, for instance the line between the mechanical centers
of the lenses, and the roll axis is the longitudinal line, in the
plane of the frames but perpendicular to the lateral axis, enabling
the frames to rotate from side to side.
[0009] Another novel aspect of the mechanics of the system is the
manner in which the frame is clamped using a scissors type of
action, whose geometry is arranged so that it clamps the frame with
the line joining the mechanical center lines of the lenses passing
through the center of the positioning pins. As a result, when the
lenses are at the measurement positions, the center of the
alignment pins, through which the measuring beam should pass,
should be on the mechanical center of the lenses.
[0010] One exemplary implementation may involve a system for
measurement of the optical properties of spectacle lenses,
comprising: [0011] (i) a source of light for transmitting a light
beam through a lens to be measured, [0012] (ii) an optical
analyzing unit for analyzing the light beam after transmission
through the lens, [0013] (iii) a lens aligner disposed in the path
of the light beam before the optical analyzing unit, the lens
aligner defining a plane perpendicular to the path of the light
beam, [0014] (iv) a mechanism for pressing the lens into position
on the lens aligner, [0015] (v) a frame gripper for gripping the
lenses of the spectacles, and [0016] (vi) a mechanical structure
adapted to enable the frame gripper, before clamping of the lens on
the lens aligner, to rotate the spectacles freely about both axes
orthogonal to that parallel to the path of the light beam.
[0017] In such a system, the lens aligner may be a set of three
alignment pins or an alignment ring.
[0018] The frame gripper may be adapted to center the lens at the
center of the lens aligner when the lens is positioned laterally
over the lens aligner. In the latter case, the frame gripper may
comprise a crossed pair of arms connected in their central region
by a pivot joint, each arm comprising a lens gripper at locations
on the arm at opposite sides of the pivot, and wherein the frame
gripper is disposed in the system such that the pivot joint lies at
the center of the lens aligner when the holder is in its central
position. The arms may conveniently comprise gripping elements at
or near their extremities, the gripping elements being adapted to
grip the edges of the lenses. Additionally, the arms may be spring
loaded in such a manner as to bias them to grip the edges of the
lenses.
[0019] The frame gripper may further comprise a ratchet locking
mechanism adapted to hold the spring-loaded arms open until the
ratchet is released. Additionally, a support wire may be provided,
positioned beneath the arms, such that the spectacles are supported
thereon while not yet gripped by the frame gripper. The pivot
should lies on a line joining the centers of both lenses of the
spectacles when gripped in the frame gripper. The position of the
pivot of the arms of the frame gripper may advantageously be
configured such that the mechanical center of each lens is aligned
longitudinally with the axis of the light beam when the lens is
positioned over the lens aligner.
[0020] Other implementations may further involve a system as
described hereinabove, wherein the lens aligner defining the plane
perpendicular to the path of the light beam enables measurement of
the lens to be performed with an accuracy independent of either of
the optical sag or tilt of the lens. Furthermore, the mechanism for
pressing the lens into position on the lens aligner may comprise a
set of spring loaded pins, each pin being disposed essentially
opposite to one of the alignment pins.
[0021] Additional implementations can include constructing the
mechanical structure to include a journal and bush bearing enabling
the frame gripper to perform roll motion, and a double pivot
assembly enabling the frame gripper to perform pitch motion and
vertical motion. In such an implementation, the journal and bush
bearing may comprise a cylindrical journal attached to the frame
gripper, adapted to rotate within a bush bearing formed in a base
assembly, the base assembly being attached to a mounting assembly
connected to horizontal and vertical movement slides on the system.
Furthermore, the double pivot assembly may comprise a base assembly
to which the frame gripper is rotatably attached, the base assembly
being attached at each of its sides by a first pivot joint to a
pivot arm, the pivot arm on each side of the double pivot assembly
being attached at an end remote from the first pivot joint by means
of a second pivot joint to a mounting assembly connected to
horizontal and vertical movement slides on the system.
Additionally, the system can further comprise an actuator element
attached to a controlled vertical motion mechanism, wherein the
mechanical structure is attached flexibly to the actuator element,
such that when the actuator element is lowered, the structural
element is also lowered. In such an embodiment, the controlled
vertical motion mechanism should also lower the mechanism for
pressing the lens into position on the lens aligner.
[0022] Any such systems may further comprise a controlled
horizontal motion mechanism, such that the frame gripper can be
moved laterally between lenses. The system can then also
incorporate control circuitry adapted to control the vertical and
horizontal motion mechanisms in conjunction with the optical
analyzing unit for analyzing the light beam after transmission
through the lens, such that the measurement of the optical
properties of spectacle lenses is performed on both lenses
sequentially and automatically.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The presently claimed invention will be understood and
appreciated more fully from the following detailed description,
taken in conjunction with the drawings in which:
[0024] FIGS. 1A and 1B illustrate schematically the positions of
spectacle lenses in a prior art lens mapper, relative to the light
beam used to measure the lens;
[0025] FIGS. 2 and 3 illustrate a lens alignment system used in the
presently described instruments, using a three point lens aligning
mechanism, comprising three alignment pins; FIG. 2 shows the lens
alignment system open, while FIG. 3 shows a system with a lens
damped in position for measurement;
[0026] FIGS. 4A and 4B are isometric engineering drawings of an
exemplary implementation of a complete lens mapping instrument,
incorporating the holding mechanisms novel to the present
application; FIG. 4A shows a front left view of the instrument,
while FIG. 4B shows a front right view of the instrument;
[0027] FIGS. 5, 6 and 7 are different views of the frame gripper
mechanism used to hold the spectacle frames in a predetermined and
centralized position; and
[0028] FIGS. 8 and 9 show the frame gripper holder mechanism for
enabling the desired limited freedom of motion of the frame gripper
of FIGS. 5 to 7; FIG. 8 shows the mechanism partly disassembled
while FIG. 9 shows the mechanism completely assembled.
DETAILED DESCRIPTION
[0029] Reference is first made to FIGS. 1A and 1B, which illustrate
schematically a problem in the use of prior art ophthalmic lens
mappers, in which the complete spectacle frame is mounted on the
measurement table. FIG. 1A shows a typically pair of conventional
spectacle frames having highly curved lenses 10, while FIG. 1B
shows a pair of spectacles, such as fashion sun-glasses, in which
the shape of the frame creates a large tilt between the lenses and
the measurement table 13. These drawings show the position of a
spectacle lens 10, 13, in such a prior art lens mapper, relative to
the light beam 11 being used to measure the lens. In such a prior
art lens meter, the alignment of the lens being measured is defined
by the alignment of the spectacle frames held flat on the
measurement table 12. This alignment can also be affected by the
overall frame shape. Consequently, in lenses having sharp surface
curvatures, or in frames having highly curved shapes, such as those
shown in FIGS. 1A and 1B, (where the different curvatures have been
exaggerated to more clearly illustrate the phenomenon) the light
will not pass through the lens normal to the optical axis of the
lens, resulting in inaccuracies of the measurement. This is
particularly problematic with negative lenses, and with
measurements made on the near vision regions of progressive lenses.
The measurement light beam is shown by the solid lines 11
perpendicular to the plane against which the spectacle frame is
pressed, whereas a more accurate lens characteristic measurement
would be obtained if the light beam were to pass through the lens
in the direction parallel to the lens optical axis, as shown by the
dashed line 14. In some prior art systems, use of a single pin
provides a way to overcome the lack of knowledge of the sag of the
lens (the height between the lens apex and the measurement
surface). However, no prior art mapping system is known to the
applicants in which the tilt of the lens has been taken into
account in mapping the lens.
[0030] FIGS. 2 and 3 now show part of an exemplary lens mapper of
the type described in the present disclosure, including a more
advantageous lens alignment system, in which the alignment of the
lens is defined such that the incident light beam is always
directed generally parallel to the optical axis of the lens, by
ensuring that it passes through the lens in a direction normal to
one of the surfaces of the lens, and at, or nearby to, the optical
center of the lens. In order to achieve such an alignment, in the
present described system the spectacle frames are inserted into the
lens measurement meter in such a manner that the lens to be
measured is held such that, up to the point at which it is clamped
in its measurement position, it is free to rotate in all
directions, with the exception of rotation around its optical axis,
which would result in inaccurate cylinder axis measurements. This
freedom of rotation is maintained while the lens is being clamped
into its measurement position on the measurement table, so that it
is clamped in the optimum position for a measurement along the
optical axis of the lens. The clamping mechanism ensures that the
lens is held in this optimum position once clamped, by the novel
lens aligning mechanisms of the present system. When reference is
made in this disclosure to the clamping of a lens or a lens frame,
it is to be understood that this is intended to include both cases
in which the clamping is performed on the frame around the lens,
and the case of frameless lenses in which the edge of the lens
itself is clamped.
[0031] Referring now to FIGS. 2 and 3 again, this is achieved in
the exemplary instrument described herein by use of a three point
lens aligning mechanism, comprising three alignment pins 20
projecting from the entry window 21 of the beam analyzing unit and
preferably arranged to be symmetrically positioned around the
central region of the lens. The upper ends of these alignment pins
define a plane perpendicular to the direction of the measurement
light beam, so that when a lens 22 is pushed into contact with
these alignment pins, it is known that at least its lower surface
lies in a plane perpendicular to the measurement light beam. This
plane is also positioned longitudinally down the optical path so
that the light refracted through the lens is correctly incident on
the Hartman Shack plate and its imaging lens. The lens is held
firmly against the three alignment pins by means of three
spring-loaded retractable pressure pins 23, known as blocker pins
arranged to descend upon the lens being measured, and push it
against the three alignment pins 20. Each of the spring-loaded
retractable pins 23 is positioned essentially opposite one of the
three alignment pins. The spring-loaded retractable pins 23 are
mounted in a pin holder 25, which is lowered when so commanded by
the system control, by means of a bracket 26 attached to a motor
driven vertical slide. The lower surface of the lens being measured
is therefore always aligned perpendicular to the measurement light
beam, and any lack of parallelism between the two surfaces, is
taken up by the spring-loaded nature of the pins 23 which contact
the upper surface of the lens. The upper and lower pins are
provided with tips 24 of a soft material such as Teflon, so that
damage is not caused to the surfaces of the lenses
[0032] The use of three pins in this manner, not only defines the
plane of the clamped lens in the optimum position for measurement,
but also leaves a clear window through the center of the lens in
order to perform the optical measurement of the lens. The
measurement beam axis should pass through the center of the
aligning pins. The construction of the blocker parts and the frame
holder parts should be such as to minimize obscuration of the Shack
Hartman matrix, or of any alternative detection mode used.
[0033] FIG. 2 shows the spectacle frame containing the lens 22 to
be mapped in its upper position, where the loading of the frames is
performed, and where the frames are moved laterally to switch
measurement between lenses. The frame is held freely suspended over
the three alignment pins. FIG. 3 shows the lens clamped in position
on the instrument, firmly held between the three alignment pins 20
and the three spring-loaded retractable pressure pins 23. Other
aspects of FIGS. 2 and 3 will be explained more fully
hereinbelow.
[0034] Although the lens alignment implementation shown in FIGS. 2
and 3 uses fixed alignment pins mounted on the optical measurement
window, and spring-loaded retractable pressure pins to descend onto
the lens to clamp it against the fixed alignment pins, it is to be
understood that these functions could equally well be reversed,
with the fixed alignment pins descending to clamp the lens onto
spring-loaded retractable pressure pins mounted on the optical
measurement window. In this case, the reference plane defining
perpendicularity to the measurement light beam is that of the upper
and hence outer surface of the lenses.
[0035] Reference is now made to FIGS. 4A and 4B which are isometric
engineering drawings of an exemplary implementation of the complete
lens measuring instrument with its covers removed, incorporating
the holding mechanisms novel to the present application. FIG. 4A
shows a front left view of the instrument, while FIG. 4B shows a
front right view of the instrument. Relevant mechanical features of
the instrument will be discussed more fully below. The spectacles
are held within the double conical frame grippers 41, being the
gripping elements of the complete frame gripper 50 attached to the
instrument by means of the articulated pivot arm 43, whose
mechanisms provide for freedom of movement of the frames up to the
instant at which they are clamped. The articulated pivot arm 43 is
supported from a carriage running on a horizontal slide 42 on the
vertical column of the instrument, the carriage being driven by an
electric motor 48 through the lead screw 49. This lateral slide
motion of the frame carrier is used in order to move the frame
laterally from one lens to the other, and to switch between
measurements of the two lenses,
[0036] The optical source for the measurements and the collimating
optics are contained within the source module 44, and the optical
beam is projected downwards through the central region of the
retractable pressure pins 45. After passing through the lens under
test, the light is analyzed, according to the exemplary
implementation shown in FIG. 4, by means of a Hartman or Hartman
Shack plate contained within the optical analysis module 46, and
the light deviation resulting from passage through the plate is
monitored by means of a CCD camera located in the base of the
optical analysis module 46. The vertical movement of the frame
carrier, used in order to lower the frames into the lens
measurement position on the optical table, and to lower the
retractable pressure pins 45 onto the lens being tested, and to
raise them once each lens has been measured, is accomplished by
means of an electric motor 47, which provides vertical motion to
the carriage on the vertical slide 39 by means of the vertical lead
screw 38. The carriage carries an actuating rod 27 which pushes a
support arm 95 by which the frame gripper is supported. The support
arm's function and mode of operation will be further explained in
connection with FIGS. 8 and 9 hereinbelow. The power supply 35 and
control circuits 34 may be located at the rear of the instrument,
on either side, as shown.
[0037] Reference is now made to FIGS. 5, 6 and 7, which illustrate
a mechanism used in order to hold the spectacle frames in the frame
carrier in a predetermined and centralized position. FIG. 5 is a
plan view showing the mechanism in an open position ready to grip a
pair of spectacle frames for measurement of its lenses. FIG. 6 is
the same view showing the mechanism closed and grasping the frame,
while FIG. 7 is an isometric view of the closed mechanism showing
how the frame is gripped in a defined position and so that it
cannot move in the direction parallel to its lens axes.
[0038] Referring back now to FIGS. 5 and 6, it is observed that the
frame gripper 50 comprises a mechanism resembling a pair of spring
loaded calipers similar in action to a pair of scissors, the two
arms 51, 52, being pivoted at the central pivot bearing, situated
behind the nose centering element 55, and hence not visible in the
drawings. The full extent of each arm of the calipers both sides of
the central pivot bearing is clearer from FIG. 6. While the caliper
arms or jaws are open, the spectacle frames lie on a frame
supporting wire 54 which supports them loosely in a horizontal
position until the frame gripper mechanism is closed to clamp them.
The frame gripper mechanism incorporates a ratcheted locking
mechanism of any suitable type known in the art in the frame
gripper support arm 58 which holds the caliper jaws open, until
applied finger pressure on the handles 57 unlatches the ratcheted
locking mechanism and allows the spring-loaded arms 51, 52 to close
onto the spectacle frames. This mechanism enables the operator to
insert the spectacle frames into the frame gripper, and to enable
them to lock in position with a single handed motion. When the
caliper arms are open, the conical frame grippers 56 are held clear
of the spectacle frames. The nose centering element 55 is spring
biased in the vertically downward direction of the drawing, i.e. in
the direction towards the handles 57, so that it maintains contact
with the lens frames in the nose gap of the frame as soon as they
are inserted into the open frame gripper, maintaining the centered
lateral position of the frames. As the caliper arms close onto the
frame, the conical frame grippers move inwards to grip the lens
frame at the edges of each lens, as shown in FIG. 6. The shape of
the cone pushes the lens frame downwards so that it sits firmly on
the frame supporting wire 54. At the same time, the nose centering
element 55 can move backwards against its spring pressure, pushed
by the lenses in the nose gap region, while maintaining constant
contact with the frame in the nose gap, thus ensuring centering of
the spectacle in the lateral left-right axis. The conical
structures of the frame grippers 56 grip the lenses positively,
being constructed of a material such as pliant silicone rubber, and
are arranged spatially such that they grip the lens with its center
line over the center of the alignment pins. This action is shown
more clearly in FIG. 7 which is an isometric view, rather than a
plan view.
[0039] The frame gripper shown in FIGS. 5 to 7 is designed to have
a number of concurrently operative positioning functions, which are
of importance in ensuring correct alignment of the frames for the
optical measurements. Firstly the nose centering element 55, by
contacting the space between the lens frames as the caliper arms
are closed, is operative to ensure that the spectacle frames are
centered laterally, i.e. in the right-left position in FIGS. 5 and
6. Secondly the pivot axis of the caliper arms is advantageously
arranged to be aligned with the lateral axis through the center of
the alignment pins, such that the pivot lies on the line joining
the optical centers of the lenses mounted therein, such that when
the frame gripper is closed, the frames are centered in the
vertical direction in the drawings so that optical measurements are
made around the optical centers of the lenses.
[0040] Once the optical measurements on the lenses are complete,
pressure on the handles 57 opens the caliper jaws again, out to a
position where the ratcheted locking mechanism in the support arm
58 holds them open again without the need for the operator to hold
them open, so that the frame may be removed.
[0041] The function of the frame gripper as shown in FIGS. 5 to 7
is to provide a convenient way in which to mount and to hold the
frames in a predefined reference position for the optical
measurements. However, as previously mentioned, one of the
important features of the instrument of the present disclosure is
that when the frames have been mounted in the frame gripper, they
should be allowed to move freely (with the exception of yaw
rotation in the horizontal plane, i.e. the plane of the lenses) so
that the alignment pins can grip each lens firmly in the required
measurement plane position without the frames exerting any
limitation on the angular or lateral position which the lenses can
adopt, and without the frames hindering the freedom of the lenses
to adopt this position. In order to accomplish this, the frame
gripper cannot, for instance, be firmly mounted on a vertical slide
attached to the horizontal slide on the vertical column of the
instrument, since this would not provide it with the desired
freedom of movement. In order to accomplish this freedom of
movement, a mechanical system is used which enables the required
tilt and roll motion of the frame gripper of several degrees, and
the vertical motion required so that each lens can adopt the
required stance for its measurement as the alignment pins lock it
into position. The vertical motion must be sufficient also to cover
the vertical range required to lower the frame gripper from its
loading position to the measurement position.
[0042] Reference is now made to FIGS. 8 and 9, which show one
exemplary implementation of a frame gripper holder mechanism for
achieving this aim. FIG. 8 shows the mechanism partly disassembled
so that its operative parts can be understood, while FIG. 9 shows
the mechanism completely assembled ready for mounting onto the
vertical column mounted horizontal slide, used for moving the
frames laterally. In the described mechanism, the roll motion is
provided by means of a circular bush bearing, while the vertical
and pitch motions are provided by means of a pair of sequentially
pivoted arms.
[0043] Referring now to FIG. 8, there are seen three sub-assembly
component parts of this complete mechanism. At the left-hand side
there is shown the frame gripper subassembly 80 comprising the
frame gripper caliper assembly 81, together with the nose centering
element 82 and its deployment mechanism 83, and the roll bearing
84. In the center of the drawing there is shown the sequentially
pivoted arm subassembly 86, which enables pitch and vertical
motion. At the right of the drawing, there is shown the mounting
subassembly 90 used to attach the entire frame gripper holder
mechanism to a horizontal slide attached to the vertical column of
the instrument, and to ensure that the frame gripper subassembly 80
is lowered to its position close to the alignment pins 20 when the
optical measurement is to be made. The structure of each of these
subassemblies is now described in terms of their functional
operation.
[0044] In order to provide roll motion to the frame gripper 81, at
the innermost (rearmost) end of the complete frame gripper
subassembly 80, there is a cylindrical bearing journal 84, which is
adapted to fit into a matching bush housing 89 located in the
center of the base section 87 of the sequentially pivoted arm
assembly 86. The fit of the bearing journal 84 into the bush 89 is
such that free rotation is permitted, but without allowing
excessive lateral or vertical motion. The journal 84 is prevented
from slipping out of the bearing 89 by means of an end plate 91,
which maintains it within the sequentially pivoted arm assembly 86.
Since the end plate 91 is attached only to the bearing journal 84,
it can rotate with roll of the frame gripper subassembly 80.
[0045] If it were necessary to provide only pitch motion to the
frame gripper 81, it would have been possible to connect the base
section 87 containing the bearing bush 89, to the mounting
subassembly and hence to the horizontal slide carriage of the
instrument by means of a single axis pivot. However besides the
pitch motion it is necessary also to provide free, uncontrolled
vertical motion. This is necessary both in order to lower the frame
gripper into its measurement position over the alignment pins, and
because it is important to allow the pitch motion to take place
around an axis centered on the alignment pins, since it is about
this point that the lenses must be allowed to freely tilt in order
to sit positively on all the alignment pins. This is achieved by
allowing vertical motion as well as pitch motion, since the
combination of the two can be projected to a pure pitch motion at a
distance from the effective pitch pivot, as required. This
combination can be achieved by connecting the base section 87 to
the mounting subassembly by means of pivot arms 88 having two pivot
axes, 92, 93 (93 is shown assembled in FIG. 9). The base section 87
is connected to one end of the pivot arms 88 at the front pivot
axes 92, allowing the base section to provide pitch rotation, while
the other end of the pivot arms are attached by the rear pivot axes
93A and 93B (shown as 2 items because of the disassembled nature of
the pivot in this assembly drawing), allowing the pivot arms to
undergo pitch motion relative to the mounting subassembly 90. This
double pivot action allows the base section not only to swivel in
the pitch direction but also to move up and downwards as the pivot
arms perform a swiveling action around their two pivot axes 92, 93,
thereby simulating both gross vertical motion and pitch motion
around the center of the alignment pins which should be close to
the pivot pin of the frame gripper. This two pivot axis motion also
requires a small movement in the inward-outward direction of the
frame holder. This movement is enabled by ensuring a little
lengthwise freedom of journal 84 in bush 89, such as by making the
journal 84 slightly longer than the length of the mating bushing
bore 89 in the base section 87. The end plate 91 limits the outward
motion of the journal 84.
[0046] In order to assist in the lowering of the frame gripper
assembly 80, so that the combined force of the spring blocker pins
23 would be enough to ensure lens contact with all three locating
pins, assist springs 98 may be advantageously used in order to
apply more downward pressure to the frame gripper assembly 80 and
thus counter the natural imbalance caused by the fact that the
center of gravity of the complete spectacle holder mechanism lies
behind the center of the locating pins, and closer to the vertical
column of the instrument. The lower ends of the spring are attached
by means of a screw 99, through an opening 100 in the pivot arms 88
to a point 101 in the central part of the base section 87. The
upper ends of the springs may be attached to a convenient fixed
post. Since the base section 87 is hinged about the front pivot
axis 92, the upward force of the springs 98 on the base section 97
will cause the frame gripper to be pushed downwards, to apply more
pressure to the alignment pins.
[0047] The mounting subassembly 90 is attached rigidly to the
carriage of the horizontal slide, which itself is mounted on the
vertical column of the instrument, while the frame gripper assembly
80 and its associated sequentially pivoted arm assembly 86 are
pivoted on the mounting subassembly 90 as described hereinabove, to
enable their independent freedom of motion. The mounting
subassembly 90 also includes component elements for lowering the
frame gripper assembly 80 in order to position the lens to be
mapped on the alignment pins 20, and to raise the frame gripper
assembly when the measurement has been performed, and it is
necessary either to move the frames laterally for the other lens to
be measured or to remove them completely from the instrument. The
weight of the pivoted combined frame gripper assembly 80 and
sequentially pivoted arm assembly 86 is supported from a pivoted
support arm 95 by means of a cord 94 attached to the frame gripper
nose centering deployment mechanism arm 83. The cord 94 may
preferably be looped in order to enable easy attachment to the
support arm 95. The support arm is attached to the mounting
subassembly 90 by means of a pivot (hidden in the views of FIGS. 8
and 9) with a bias spring 96 which holds the support arm 95 in its
raised position unless pushed downwards. The upper position of the
complete frame gripper assembly 80 and mounting subassembly is
limited by the edge 97 of the limit plate, which prevents the
spring 96 from pulling the assemblies even higher. The spectacle
frame mounted in the frame gripper 81 is thus held clear of the
alignment pins unless the support arm 95 is pushed downwards, which
occurs when a lens measurement needs to be made. The manner in
which this will be accomplished is described hereinbelow.
[0048] FIG. 9 now shows the mechanism completely assembled ready
for mounting onto the horizontal slide carriage on the vertical
column of the instrument. All of the component parts are labeled
with the reference characters as used in the assembly drawing of
FIG. 8.
[0049] Reference is now made back to FIGS. 2 and 3, to illustrate
how the frame gripper is moved from its loading, upper position, to
its measuring, lower position with the lens firmly clamped on the
alignment pins. In FIG. 2, there is seen the support arm 95 and its
associated cord 94 supporting the frame gripper with all of its
component assemblies, held in the upper position by virtue of the
bias spring 96 of FIGS. 8 and 9. The spring loaded support arm is
constrained at its upper limit by virtue of the edge 97 of the
limit plate. As the instrument control moves the spring loaded
retractable pin assembly 25 down in order to prepare for a
measurement, an actuator rod 27 attached to the bracket 26, moves
down with motion of the bracket, and pushes downwards on the
support arm 95, either directly or by means of a rigid link,
allowing the frame gripper assembly to descend also. This is
clearly shown in FIG. 3, where the frame gripper assembly is at its
measurement position, with the alignment pins 20, 23 clamping the
lens in position. As is observed, the actuator rod 27 has pushed
the support arm 95 to its lower position, and the frame gripper
subassembly 80 is clear of the edge 97 of the limit plate. The
complete frame gripper assembly position is now defined by the
pressure of the alignment pin assemblies 20, 23 on the lens being
measured, as assisted by the assist springs 98.
[0050] One example of an operating sequence by which the instrument
can be used in order to perform a complete automatic mapping
sequence of the lenses of a pair of spectacles is now described.
The user inserts the spectacle frames in the frame gripper in its
home position, this being most conveniently at the center of the
lateral travel, the insertion procedure being a simple one-handed
operation. Once the frames are correctly located in the frame
gripper, the instrument can be started, and the rest of the
procedure may be performed automatically by the instrument
controller. The first step is for the lateral slide motion to move
the frame gripper laterally from the home position until one lens
is positioned over the aligning pins. The motion may typically be
stopped at the correct position by use of a limit switch. Then the
vertical slide control lowers the frame gripper into position, with
the first lens clamped by the alignment pins and centered over the
optical window for mapping. Once this mapping image has been
obtained, the blocker pins 23 are raised, together with the frame
gripper, and the horizontal drive moves the frame gripper by the
predetermined distance, generally chosen to be the 63mm standard
pupil distance measurement, (though any other distance can be
entered into the control for differing circumstances) so that the
second lens is now centered over the optical measurement channel.
The motor may most conveniently be a stepping motor. The procedure
is then automatically repeated for the second lens, and when
complete, the frame gripper and blocker pins are raised, and the
frame gripper moves to its home position in the center of the
instrument travel to enable the frame to be released from the frame
gripper.
[0051] Since operation of the instrument is automatic, a number of
sensors should be advantageously used in the instrument. In the
first place, the horizontal and vertical slide drives should be
protected from end overruns, by means of limit switches, such as
that 36 shown in FIG. 4A on the vertical slide. Stepping motors and
encoders can be used to provide positive control of the slide
position at all times.
[0052] In addition, frame arm sensors 32 can be located on either
side of the analyzing module of the instrument, to detect when the
lateral motion of the frame gripper is such that the frame arm
intersects the line of sight of the sensors 32, at which point, the
motion should be stopped. This feature is important when, for
instance, children's frames are measured.
[0053] It is appreciated by persons skilled in the art that the
present invention is not limited by what has been particularly
shown and described hereinabove. Rather the scope of the present
invention includes both combinations and subcombinations of various
features described hereinabove as well as variations and
modifications thereto which would occur to a person of skill in the
art upon reading the above description and which are not in the
prior art.
* * * * *